Removable dishwasher filtration system

ABSTRACT

A dishwasher having a removable filtration system includes a main coarse filter screen having a central opening for removably fitting the filter screen around a water distribution manifold. The filter screen includes an outer circumferential rim portion have an elastomeric seal over-molded thereto which is press-fit into a channel in a lower sump unit such that the filter screen is suspended over a sump enclosure. A finer, secondary strainer extends through the filter screen and provides secondary filtering of washing fluid entering the sump enclosure through the filter screen. Preferably, the filtration system also includes a non-removable or backup strainer which provides coarse straining of washing fluid should a user fail to properly reinstall the removable filter screen and/or the secondary strainer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the art of dishwashers and, more specifically, to a dishwasher including a removable filtration system.

2. Description of the Related Art

Dishwashers for use in the home typically have a filter arrangement to filter material from wash liquid circulating in the dishwasher to prevent such material from re-depositing on dishware being washed. Many dishwashers have at least one filter interposed between a tub sump and the circulation pump for the dishwasher. Some dishwashers are known to have a bypass filter arrangement, such as a flow-through filtration system, independent of the circulation pump, to filter wash liquid upstream of the circulation pump. Flow-through filtration wash systems require periodic removal of filter screens for cleaning by a consumer. Consumers are expected to remove, clean and properly reinstall filter components on a regular basis. However, problems may occur when a consumer fails to replace the filters properly before a new wash cycle. For example, dishwasher spray nozzles may become plugged with debris, causing significant performance degradation and potentially requiring professional repair of the machine. Additionally, debris may collect around the rim of a removable filter screen or may even bypass the filter screen if a proper seal is not maintained between the filter screen and its support base. Again, performance of the dishwasher may be degraded by such debris entering the pump and distribution systems of the dishwasher.

With the above in mind, there exists the need for an inexpensive and easy-to-use dishwasher filtration system that provides further protection against damage from debris entering the dishwasher's pump and distribution system.

SUMMARY OF THE INVENTION

The present invention is directed to a dishwasher having a removable filtration system. In general, the removable filtration system includes a main coarse filter screen having a central opening for removably fitting the filter screen around a water distribution manifold. The filter screen includes an outer circumferential edge have an elastomeric, over-molded seal which can be press-fit into a channel in a lower sump unit such that the filter screen is suspended over a sump enclosure. When installed, a top wall of the over-molded seal is substantially flush with a top wall of the sump unit, thus preventing debris from bypassing the filter screen or accumulating around the peripheral edge of the filter screen. The filter screen further includes an aperture through which a secondary strainer extends into the sump enclosure. The secondary strainer provides finer filtering of washing fluid entering the sump enclosure through the filter screen, as well as providing a course screen for over-flow protection. Preferably, the filtration system also includes a non-removable or backup strainer which provides coarse straining of washing fluid should a user fail to properly reinstall the removable filter screen and/or secondary strainer, or should one of the filter screen or strainer become damaged.

Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a dishwasher constructed in accordance with the present invention, with a door of the dishwasher being open;

FIG. 2 is a partial perspective view of a water distribution and filtration system of the dishwasher of FIG. 1;

FIG. 3 is a partial exploded view of the removable filtration system of the present invention;

FIG. 4 is a partial cross-sectional view of a removable filter screen of the present invention;

FIG. 5 is a top perspective view of a sump system of the dishwasher of FIG. 1;

FIG. 6 is a top perspective view of the sump system of FIG. 5 including a non-removable filter of the present invention; and

FIG. 7 is a perspective view of the non-removable filter of FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With initial reference to FIGS. 1 and 2, a dishwasher constructed in accordance with the present invention as generally indicated at 2. As shown, dishwasher 2 includes a tub 5 which is preferably molded of plastic so as to include integral bottom, side, and rear walls 8-11 respectively, as well as a top wall (not shown). Tub 5 defines a washing chamber 14 within which soiled kitchenware is adapted to be placed upon shiftable upper and lower racks (not shown), with the kitchenware being cleaned during a washing operation in a manner widely known in the art. Tub 5 has attached thereto a pivotally supported door 20 used to seal chamber 14 during the washing operation. In connection with the washing operation, door 20 is preferably provided with a detergent tray assembly 23 within which a consumer can place liquid or particulate washing detergent for dispensing at predetermined portions of the washing operation. Of course, dispensing detergent in this fashion is known in the art such that this arrangement is only being described for the sake of completeness.

Disposed within tub 5 is a filtration system generally indicated at 30. In the preferred embodiment, filtration system 30 includes a central main strainer or filter screen 36 and a secondary, fine strainer 39. Extending about a substantial portion of filtration system 30, at a position raised above bottom wall 8, is a heating element 44. In a manner known in the art, heating element 44 preferably takes the form of a sheath, electric resistance-type heating element.

Dishwasher 2 further includes a circulation pump (not shown) adapted to direct washing fluid from a sump unit 50 (best seen in FIGS. 5 and 6) to a water distribution manifold indicated at 53. In a manner known in the art, water distribution manifold 53 supplies washing fluid to at least a lower wash arm 55 and a conduit 57 leading to an upper spray arm (not shown). Additionally, water distribution manifold 53 may be in fluid communication with a spray manifold assembly 59 including a plurality of spray discs 62. The manner in which wash arm 54 and spray manifold assembly 59 are utilized is known in the art, such that this structure will not be described further herein.

Details of sump unit 50 utilized in dishwasher 2 are depicted in FIGS. 3-6. Sump unit 50 generally comprises a sump enclosure 68 with filter screen 36 preferably disposed over a top opening of enclosure 68, and a recessed main intake 73 having an outlet 80 leading to a circulation pump (not shown) for circulating fluid through water distribution manifold 53 to wash arm 55, conduit 57 and manifold assembly 59. In accordance with the present invention, a filter support surface 83 extends around the upper perimeter of sump enclosure 68. Filter 36 is supported along its outer circumferential edge 90 by filter support surface 83 and seals against filter support surface 83 in a manner more fully discussed below.

Filter screen 36 is substantially circular and includes a main body portion 100 have an aperture 105 there through, and arm portions 108 and 109 which define a central opening 112 in the form of a slot there between. As depicted best in FIG. 3, central opening 112 of filter screen 36 fits around water distribution manifold 53. Filter screen 36 preferably constitutes a first-pass coarse screen having a shape that aids in channeling wash liquid. More specifically, filter screen 36 includes a dam portion indicated at 123 which aids in channeling a flow of washing fluid across filter screen 36 to secondary strainer 39. Additionally, filter screen 36 is oriented with respect to sump unit 50 such that outer circumferential edge 90 is at a greater height than an inner filter edge 126 of aperture 105. The resulting downwardly sloping configuration of filter screen 36 facilitates the flow of washing fluid to sump unit 50 and the distribution of food particles or debris across filter screen 36.

As depicted in FIG. 4, outer circumferential edge 90 of filter screen 36 comprises an inwardly curved flange portion 130 that basically establishes an open loop. An annular elastomeric seal 133 extends about substantially the entire outer surface of flange portion 130, with seal 133 including a bottom wall 136, a side wall 137 and a top wall portion 138. In the preferred embodiment of the present invention, seal 133 is constituted by an over-molded flexible rubber seal. Support surface 83 is generally defined by a bottom wall portion 140 extending laterally from a sidewall 143 of sump unit 50, and an upstanding wall portion 146 extending vertically from bottom wall portion 140. Together, bottom wall portion 140 and side wall 143 define a channel 150 into which outer circumferential edge 90 of filter screen 36 can be inserted. Preferably, channel 150 is further defined by an upstanding side wall portion 152 extending from side wall 143, with seal 133 directly abutting side wall portion 152.

Filter screen 36 is preferably somewhat flexible in nature, allowing for some flexing of inwardly curved flange portion 130 and the integrated seal 133. In use, arm portions 108 and 109 of filter screen 36 are fit around water distribution manifold 53 and outer circumferential edge 90 is press-fit into channel 150 such that seal 133 fits snuggly within channel 150, i.e., directly abuts bottom wall 136 and is slightly compressed between side walls 137 and 152, while top wall portion 138 of seal 133 is substantially flush with a top wall portion 158 of sump unit 50. With this configuration, food and debris will not be able to collect between filter screen 36 and sump unit 50 at outer circumferential edge 90, nor will food or debris be able to bypass filter screen 36 by flowing around outer circumferential edge 90. Additionally, over-molded seal 133 cannot be lost or improperly positioned with respect to filter screen 36, allowing for quick and easy installation of filter screen 36 within channel 150.

During normal operation, wash water flows through filter screen 36 into sump enclosure 68 and larger food particles from dishes or tableware disposed in dishwasher 2 collect on filter screen 36. Wash fluid within enclosure 68 is further filtered by secondary strainer 39 before exiting into main intake 73. In a preferred embodiment, secondary strainer 39 includes a twist lock feature wherein secondary strainer 39 includes flanges (not shown) which engage sump enclosure 68 about the periphery of intake 73 to selectively lock secondary strainer 39 in place. However, other locking arrangements that accommodate the easy removal of secondary strainer 29 could be employed. In any case, sump enclosure 68 is sloped such that fluid therein is directed to a fine screen portion 162 of secondary strainer 39 before entering main intake 73. Secondary strainer 39 also works as a main filter bypass should wash fluid become backed-up within washing chamber 14. More specifically, if wash fluid cannot flow sufficiently through filter screen 36, the level of fluid within washing chamber 14 will rise slightly to the height of inlets 166 located about the periphery of secondary strainer 39. Wash fluid will then flow through inlets 166 through a coarse screen portion 168 of secondary strainer 39 and into main intake 73. In a manner known in the art, wash fluid exits main intake 73 through outlet 80 and is recirculated within dishwasher 2 via a circulation pump (not shown). If filter screen 36 becomes plugged or blocked, a user may simply lift secondary strainer 39 clear of filter screen 36 and remove filter screen 36 from dishwasher 2 for cleaning. Likewise, secondary strainer 39 may be removed and cleaned by a user when desired and replaced for the next wash cycle.

In the case where a user forgets or fails to return filter screen 36 and/or secondary strainer 39 to their proper positions within dishwasher 2, or in the case where either one or both of filter screen 36 and secondary strainer 39 becomes damaged, washing fluid flowing through intake 73 will still be filtered before entering outlet 80 by a non-removable or back-up strainer 170, depicted in FIGS. 6 and 7. Non-removable strainer 170 is preferably permanently fixed, or at least designed such that a user cannot easily remove strainer 170 from dishwasher 2 and is arcuate in shape to conform to the arc around inlet 80. Optionally, non-removable strainer 170 may be adapted to be retrofit within intake 73. Preferably, non-removable strainer 170 includes a coarse screen 173 adapted to prevent debris from entering outlet 80 that would be potentially damaging to the fluid distribution system of dishwasher 2.

Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, although depicted as generally circular in shape, it should be understood that a variety of screen shapes could be utilized with the present invention. In general, the invention is only intended to be limited by the scope of the following claims. 

1. A dishwasher having a removable dishwasher filtration system comprising: a tub defining a washing chamber; a water distribution manifold in communication with at least one spray arm; a sump unit within the washing chamber including a support surface having a bottom wall and a side wall defining a channel; a filter screen having a main body portion including an aperture therein and an outer rim portion having an integrated elastomeric seal positioned in the channel in sealed engagement with the support surface such that the filter screen is held suspended by the engagement of the outer rim portion with the support surface, wherein the filter screen is adapted to filter debris from wash liquid entering the sump unit from the tub; and a secondary strainer extending into the aperture in the screen and being readily removable therefrom for cleaning purposes, the secondary strainer being adapted to remove debris from wash liquid passing the filter screen and flowing through the sump unit.
 2. The dishwasher according to claim 1, wherein the filter screen is substantially circular and includes first and second arm portions which define a central opening through which the water distribution manifold extends.
 3. The dishwasher according to claim 2, wherein the first and second arm portions form a slot which leads to the central opening.
 4. The dishwasher according to claim 1, wherein the elastomeric seal is constituted by an over-molded rubber seal.
 5. The dishwasher according to claim 4, wherein the outer rim portion of the filter screen includes a downwardly turned flange about which the elastomeric seal is over-molded.
 6. The dishwasher according to claim 5, wherein the downwardly turned flange curves radially inwardly.
 7. The dishwasher according to claim 5, wherein the downwardly turned flange and the elastomeric seal are flexible, with the outer rim portion being press-fit into the channel, thereby preventing debris from bypassing the filter screen.
 8. The dishwasher according to claim 1, wherein the elastomeric seal includes a top wall portion which is substantially flush with a top wall portion of the sump unit when the outer rim portion is mounted in the channel.
 9. The dishwasher according to claim 8, wherein the elastomeric seal further includes a bottom wall portion and both inner and outer side wall portions.
 10. The dishwasher according to claim 9, wherein the channel is further defined by another side wall which is spaced radially from the side wall, said elastomeric seal being slightly compressed between the side wall and the another side wall within the channel to retain the filter screen in place.
 11. The dishwasher according to claim 1, wherein the filter screen is flexible.
 12. The dishwasher according to claim 11, wherein the filter screen is readily removable from the sump unit for cleaning purposes.
 13. The dishwasher according to claim 1, wherein the sump unit comprises a recessed main intake including an outlet, said secondary strainer extending into the main intake.
 14. The dishwasher according to claim 13, further comprising: a non-removable strainer mounted directly adjacent the outlet of the main intake, wherein the non-removable strainer is adapted to prevent coarse debris from entering the outlet.
 15. The dishwasher according to claim 1, wherein the filter screen comprises a dam portion which channels fluid toward the secondary strainer.
 16. A method of assembling a filtration system in a dishwasher having a tub defining a washing chamber and a sump unit below the washing chamber comprising: mounting a filter screen within the washing chamber by positioning an elastomeric seal provided on an outer rim portion of the filter screen in sealing engagement with support surfaces which define a channel of the sump unit; and fitting a removable secondary strainer into an aperture provided in the filter screen, with the removable secondary strainer extending into a recessed main intake portion of the sump unit to remove debris from wash liquid passing the filter screen and flowing through the sump unit.
 17. The method of claim 16, wherein mounting the filter screen constitutes press-fitting a flexible outer rim portion of the filter screen, about which the elastomeric seal is over-molded, into the channel.
 18. The method of claim 17, wherein the elastomeric seal is compressed within the channel.
 19. The method of claim 16 wherein, upon mounting the filter screen, a water distribution manifold extends into a central aperture formed in the filter screen.
 20. The method of claim 16, further comprising: fitting a non-removable strainer directly adjacent an outlet of the main intake portion to prevent coarse debris from entering the outlet. 